If you bridge them, that will create an L2 loop (as EOIP are L2 interfaces). That is why OSPF was complaining about receiving locally originated packets.
Also, watch for the MTU on the EOIP interfaces, to avoid fragmentation.
All in all, I really recommend L2TP/IPSec with OSPF for all routing needs.
Yes, L2TP has a bug with replying from a wrong address, but its easily solved with NAT.
Look here for a solution: http://forum.mikrotik.com/t/management-vrfs-l2tp-server-not-replying-from-correct-ip/67201/1